1. Field of the Invention
The subject application concerns an improved electromagnetic actuator or coil assembly for a fuel injector of an internal combustion engine. The improved actuator assembly is a dry coil type in which the actuator's electrical parts are isolated from contact with fuel. Specifically, a bobbin part of the actuator is made of fuel compatible material and is configured to be closely received in a recess defined by the associated fuel injector housing. Seal between the bobbin and the housing prevent passage of fuel to electrical components of the actuator.
2. Description of Related Art
In the engine fuel injection art, it is known to use an electromagnetic actuator for operating a valving device. However, a typical prior fuel injector provides a wet actuator type design in which the entire electromagnetic actuator is exposed to fuel. This design necessitates that the entire actuator structure be able to withstand exposure to fuels such as gasoline, methanol and other alcohols. Resultantly, expensive and sometimes hard to work with materials must be employed to withstand long term exposure to fuels. Also, special wire coating for the coil must protect the wire and small seals are employed to seal the joint between the terminals and the structure. Therefore, a dry type injector design would be highly desirable. In a dry type, the parts of the actuator, particularly electrical parts, are not contacted by fuel.